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Burns K, Draghici AE, Taylor JA. Responses to Valsalva's maneuver in spinal cord injury do not broadly relate to vasoconstrictor capacity. Clin Auton Res 2024:10.1007/s10286-024-01060-1. [PMID: 39300002 DOI: 10.1007/s10286-024-01060-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 08/27/2024] [Indexed: 09/22/2024]
Abstract
PURPOSE A blood pressure stabilization during late phase II of Valsalva's maneuver may be utilized to confirm sympathetic vasoconstrictor control after a spinal cord injury. This study investigated whether Valsalva response was predictive of hemodynamics during tilt or isometric handgrip. METHODS Presence/absence of Valsalva response was compared to heart rate, mean arterial pressure, leg blood flow, and vascular resistance during head-up tilt and isometric handgrip to fatigue in 14 adults with spinal cord injury from C7 to T12 and 14 controls. Statistics were performed with two-way repeated measure analysis of variance (ANOVA), post hoc t-tests for between-group comparisons, and Mann-Whitney U tests for within-group. RESULTS In total, six participants with spinal cord injury lacked a blood pressure stabilization for Valsalva's maneuver. However, this was not related to vasoconstrictor responses during the other tests. The groups had similar heart rate and blood pressure changes during tilt, though leg blood flow decreases and vascular resistance increases tended to be smaller at 20° tilt in those with spinal cord injury (p = 0.07 and p = 0.11, respectively). Participants with spinal cord injury had lower heart rates and markedly smaller blood pressure increases during handgrip (both p < 0.05). There were no group differences in leg blood flow, but those with spinal cord injury demonstrated a blunted vascular resistance increase by the final 10% of the handgrip (p < 0.01). CONCLUSIONS Valsalva response was not consistent with hemodynamics during other stimuli, but some individuals evidence increases in sub-lesional vascular resistance to isometric handgrip comparable to controls, suggesting a sympathoexcitatory stimulus may be critical to provoke hemodynamic responses after spinal cord injury.
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Affiliation(s)
- Kathryn Burns
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, 1575 Cambridge Street, Cambridge, MA, 02138, USA
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, USA
| | - Adina E Draghici
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, 1575 Cambridge Street, Cambridge, MA, 02138, USA.
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, USA.
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA.
| | - J Andrew Taylor
- Cardiovascular Research Laboratory, Spaulding Hospital Cambridge, 1575 Cambridge Street, Cambridge, MA, 02138, USA
- Schoen Adams Research Institute at Spaulding Rehabilitation, Boston, MA, USA
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, USA
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Jacob DW, Morgenthaler LD, Harper JL, Limberg JK. The forearm vascular response to sympathetic activation is attenuated in female, but not male, participants following acute intermittent hypoxia. J Appl Physiol (1985) 2023; 135:352-361. [PMID: 37410902 PMCID: PMC10396222 DOI: 10.1152/japplphysiol.00760.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 06/05/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023] Open
Abstract
Acute exposure to hypoxia promotes both an increase in sympathetic nervous system activity (SNA) and local vasodilation. In rodents, intermittent hypoxia (IH)-mediated increases in SNA are associated with an increase in blood pressure in males but not females; notably, the protective effect of female sex is lost following ovariectomy. These data suggest the vascular response to hypoxia and/or SNA following IH may be sex- and/or hormone specific-although mechanisms are unclear. We hypothesized that hypoxia-mediated vasodilation and SNA-mediated vasoconstriction would be unchanged following acute IH in male adults. We further hypothesized that hypoxic vasodilation would be augmented and SNA-mediated vasoconstriction would be attenuated in female adults following acute IH, with the greatest effect when endogenous estradiol was high. Twelve male (25 ± 1 yr) and 10 female (25 ± 1 yr) participants underwent 30 min of IH. Females were studied in a low (early follicular) and high (late follicular) estradiol state. Preceding and following IH, participants completed two trials [steady-state hypoxia and cold pressor test (CPT)], where forearm blood flow and blood pressure were measured and used to determine forearm vascular conductance (FVC). The FVC response to hypoxia (P = 0.67) and sympathetic activation (P = 0.73) were unchanged following IH in males. There was no effect of IH on hypoxic vasodilation in females, regardless of estradiol state (P = 0.75). In contrast, the vascular response to sympathetic activation was attenuated in females following IH (P = 0.02), independent of estradiol state (P = 0.65). Present data highlight sex-related differences in neurovascular responsiveness following acute IH.NEW & NOTEWORTHY We examined the effects of acute intermittent hypoxia (AIH) on the vascular response to sympathetic activation and acute hypoxia. Present findings show, despite no effect of AIH on the vascular response to hypoxia, the forearm vasoconstrictor response to acute sympathetic activation is attenuated in females following AIH, independent of estradiol state. These data provide mechanistic understanding of potential benefits of AIH, as well as the impact of biological sex.
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Affiliation(s)
- Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Leandra D Morgenthaler
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri, United States
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, United States
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Jacob DW, Voshage AM, Harper JL, Limberg JK. Effect of oral hormonal contraceptive pill use on the hemodynamic response to the cold pressor test. Am J Physiol Heart Circ Physiol 2022; 322:H1072-H1079. [PMID: 35486478 PMCID: PMC9142154 DOI: 10.1152/ajpheart.00140.2022] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 11/22/2022]
Abstract
Acute increases in sympathetic nervous system activity (SNA) often elicit peripheral vasoconstriction and increases in blood pressure (BP). Given sympathetic support of BP is modulated by ovarian sex hormones (e.g., estradiol), we sought to examine the effect of menstrual cycle and oral hormonal contraceptive pill (OC) phase on the hemodynamic response to acute increases in SNA. We hypothesized sympathoexcitation via cold pressor test (CPT) would elicit greater peripheral vasoconstriction and increases BP in females with natural menstrual cycles (NC) compared with females taking OC. We further hypothesized that SNA-mediated vasoconstriction would be attenuated during the high estradiol (HE) phase versus the low estradiol (LE) phase of the menstrual/pill cycle. Female NC (n = 11, 25 ± 1 yr) and OC (n = 10, 24 ± 1 yr) participants were studied during the LE (early follicular, placebo pill) and HE (late follicular, active pill) phase of the menstrual/pill cycle. BP (finger photoplethysmography), heart rate (HR, ECG), and forearm blood flow (FBF, venous occlusion plethysmography) were measured during a 5-min baseline and a 2-min CPT. CPT elicited an increase in BP in both groups (time, P < 0.01). During CPT, OC participants exhibited greater and sustained increases in HR compared with NC participants (group × time, P < 0.01). Higher HRs were met with increases in FBF in OC participants during the CPT, which was not observed in NC participants (group × time, P < 0.01). OC participants exhibit greater increases in HR, and paradoxical vasodilation during acute sympathetic activation compared with NC participants. Group differences are unaffected by menstrual/pill phase.NEW & NOTEWORTHY Acute increases in sympathetic nervous system activity often elicit peripheral vasoconstriction and increases in blood pressure (BP). Given sympathetic support of BP is modulated by ovarian sex hormones (e.g., estradiol), we sought to examine the effect of menstrual cycle and oral hormonal contraceptive pill (OC) phase on the hemodynamic response to acute increases in sympathetic nervous system activity via the cold pressor test. We show OC participants exhibit paradoxical vasodilation during acute sympathetic activation compared with participants with natural menstrual cycles; notably, group differences were unaffected by menstrual/pill phase.
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Affiliation(s)
- Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Aaron M Voshage
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
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Jacob DW, Harper JL, Ivie CL, Ott EP, Limberg JK. Sex differences in the vascular response to sympathetic activation during acute hypoxaemia. Exp Physiol 2021; 106:1689-1698. [PMID: 34187092 DOI: 10.1113/ep089461] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/23/2021] [Indexed: 12/22/2022]
Abstract
NEW FINDINGS What is the central question of this study? Sympathetically mediated vasoconstriction is preserved during hypoxaemia in humans, but our understanding of vascular control comes from predominantly male cohorts. We tested the hypothesis that young women attenuate sympathetically mediated vasoconstriction during steady-state hypoxaemia, whereas men do not? What is the main finding and its importance? Sympathetically mediated vasoconstriction is preserved or even enhanced during steady-state hypoxia in young men, and the peripheral vascular response to sympathetic activation during hypoxaemia is attenuated in young women. These data advance our understanding of sex-related differences in hypoxic vascular control. ABSTRACT Activation of the sympathetic nervous system causes vasoconstriction and a reduction in peripheral blood flow. Sympathetically mediated vasoconstriction may be attenuated during systemic hypoxia to maintain oxygen delivery; however, in predominantly male participants sympathetically mediated vasoconstriction is preserved or even enhanced during hypoxaemia. Given the potential for sex-specific differences in hypoxic vascular control, prior results are limited in application. We tested the hypothesis that young women attenuate sympathetically mediated vasoconstriction during steady-state hypoxaemia, whereas men do not. Healthy young men (n = 13, 25 ± 4 years) and women (n = 11, 24 ± 4 years) completed two trials consisting of a 2-min cold pressor test (CPT, a well-established sympathoexcitatory stimulus) during baseline normoxia and steady-state hypoxaemia. Beat-to-beat blood pressure (finger photoplethysmography) and forearm blood flow (venous occlusion plethysmography) were measured continuously. Total and forearm vascular conductance (TVC and FVC, respectfully) were calculated. A change (Δ) in TVC and FVC from steady-state during the last 1 min of CPT was calculated and differences between normoxia and systemic hypoxia were assessed. In men, the reduction in TVC during CPT was greater during hypoxia compared to normoxia (ΔTVC, P = 0.02), whereas ΔTVC did not differ between conditions in women (P = 0.49). In men, ΔFVC did not differ between normoxia and hypoxia (P = 0.92). In women, the reduction in FVC during CPT was attenuated during hypoxia (ΔFVC, P < 0.01). We confirm sympathetically mediated vasoconstriction is preserved or enhanced during hypoxaemia in young men, whereas peripheral vascular responsiveness to sympathetic activation during hypoxaemia is attenuated in young women. The results advance our understanding of sex-related differences in hypoxic vascular control.
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Affiliation(s)
- Dain W Jacob
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Jennifer L Harper
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Clayton L Ivie
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Elizabeth P Ott
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, USA
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Convertino VA, Koons NJ, Suresh MR. Physiology of Human Hemorrhage and Compensation. Compr Physiol 2021; 11:1531-1574. [PMID: 33577122 DOI: 10.1002/cphy.c200016] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hemorrhage is a leading cause of death following traumatic injuries in the United States. Much of the previous work in assessing the physiology and pathophysiology underlying blood loss has focused on descriptive measures of hemodynamic responses such as blood pressure, cardiac output, stroke volume, heart rate, and vascular resistance as indicators of changes in organ perfusion. More recent work has shifted the focus toward understanding mechanisms of compensation for reduced systemic delivery and cellular utilization of oxygen as a more comprehensive approach to understanding the complex physiologic changes that occur following and during blood loss. In this article, we begin with applying dimensional analysis for comparison of animal models, and progress to descriptions of various physiological consequences of hemorrhage. We then introduce the complementary side of compensation by detailing the complexity and integration of various compensatory mechanisms that are activated from the initiation of hemorrhage and serve to maintain adequate vital organ perfusion and hemodynamic stability in the scenario of reduced systemic delivery of oxygen until the onset of hemodynamic decompensation. New data are introduced that challenge legacy concepts related to mechanisms that underlie baroreflex functions and provide novel insights into the measurement of the integrated response of compensation to central hypovolemia known as the compensatory reserve. The impact of demographic and environmental factors on tolerance to hemorrhage is also reviewed. Finally, we describe how understanding the physiology of compensation can be translated to applications for early assessment of the clinical status and accurate triage of hypovolemic and hypotensive patients. © 2021 American Physiological Society. Compr Physiol 11:1531-1574, 2021.
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Affiliation(s)
- Victor A Convertino
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
| | - Natalie J Koons
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
| | - Mithun R Suresh
- Battlefield Healthy & Trauma Center for Human Integrative Physiology, United States Army Institute of Surgical Research, JBSA San Antonio, Texas, USA
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Al Dera H, Brock JA. Changes in sympathetic neurovascular function following spinal cord injury. Auton Neurosci 2017; 209:25-36. [PMID: 28209424 DOI: 10.1016/j.autneu.2017.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 01/31/2017] [Accepted: 02/09/2017] [Indexed: 12/31/2022]
Abstract
The effects of spinal cord injury (SCI) on sympathetic neurovascular transmission have generally been ignored. This review describes changes in sympathetic nerve-mediated activation of arterial vessels to which ongoing sympathetic activity has been reduced or silenced following spinal cord transection in rats. In all vessels studied in rats, SCI markedly enhanced their contractile responses to nerve activity. However, the mechanisms that augment neurovascular transmission differ between the rat tail artery and mesenteric artery. In tail artery, the enhancement of neurovascular transmission cannot be attributed to changes in sensitivity of the vascular muscle to α1- or α2-adrenoceptor agonists. Instead the contribution of L-type Ca2+ channels to activation of the smooth muscle by nerve-released noradrenaline is greatly increased following SCI. By contrast, mesenteric arteries from SCI rats had increased sensitivity to phenylephrine but not to methoxamine. While both phenylephrine and methoxamine are α1-adrenoceptor agonists, only phenylephrine is a substrate for the neuronal noradrenaline transporter. Therefore the selective increase in sensitivity to phenylephrine suggests that the activity of the neuronal noradrenaline transporter is reduced. While present evidence suggests that sympathetic vasoconstrictor neurons do not contribute to the normal regulation of peripheral resistance below a complete SCI in humans, the available evidence does indicate that these experimental findings in animals are likely to apply after SCI in humans and contribute to autonomic dysreflexia.
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Affiliation(s)
- Hussain Al Dera
- Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia
| | - James A Brock
- Department of Anatomy and Neuroscience, University of Melbourne, Victoria 3010, Australia.
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Rianne Ravensbergen HJ, de Groot S, Post MW, Bongers-Janssen HM, van der Woude LH, Claydon VE. Is There an Association Between Markers of Cardiovascular Autonomic Dysfunction at Discharge From Rehabilitation and Participation 1 and 5 Years Later in Individuals With Spinal Cord Injury? Arch Phys Med Rehabil 2016; 97:1431-1439. [PMID: 27084265 DOI: 10.1016/j.apmr.2016.03.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Revised: 03/14/2016] [Accepted: 03/19/2016] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine whether physical activity and participation 1 and 5 years after discharge are associated with measures of cardiovascular autonomic function: prevalence of hypotension and reduced peak heart rate at discharge from initial inpatient spinal cord injury (SCI) rehabilitation. DESIGN Prospective cohort study. SETTING Rehabilitation centers. PARTICIPANTS Individuals with SCI (N=146). INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES We recorded markers of cardiovascular autonomic dysfunction (resting blood pressure and peak heart rate) and personal and lesion characteristics at the time of discharge from rehabilitation. Parameters for participation (social health status dimension of the Sickness Impact Profile) and physical activity (Physical Activity Scale for Individuals with Physical Disabilities [PASIPD]) were measured 1 and 5 years after discharge. Effects of prevalence of cardiovascular autonomic dysfunction were analyzed using linear regression analysis while correcting for possible confounders. RESULTS We found no significant association between hypotension and social health status dimension of the Sickness Impact Profile or PASIPD, either at 1 or at 5 years after discharge. A significant association between peak heart rate and social health status dimension of the Sickness Impact Profile was found at 1 year after discharge, showing poorer participation in individuals with low peak heart rate (ie, cardiovascular autonomic dysfunction). The unadjusted relation between peak heart rate and the social health status dimension of the Sickness Impact Profile was significant at 5 years, but not when adjusted for confounders. We found associations between peak heart rate and PASIPD for both 1 and 5 years after discharge; however, these were not significant after correction for potential confounding factors. CONCLUSIONS Autonomic dysfunction after SCI is a crucial factor influencing quality of life. We found that cardiovascular autonomic impairment, assessed from low peak heart rate, was associated with reduced participation after 1 year. The results suggest that peak heart rate at discharge from rehabilitation after SCI should be used to identify those needing additional support to facilitate physical activity and participation after discharge.
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Affiliation(s)
- H J Rianne Ravensbergen
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada; International Collaboration On Repair Discoveries, Vancouver, BC, Canada; Research Institute MOVE Amsterdam, Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands
| | - Sonja de Groot
- Amsterdam Rehabilitation Research Center
- Reade, Amsterdam, The Netherlands; Center for Human Movement Sciences Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Marcel W Post
- Brain Center Rudolf Magnus and Center of Excellence in Rehabilitation Medicine, University Medical Center Utrecht and De Hoogstraat, Utrecht, The Netherlands; Center for Rehabilitation, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | - Lucas H van der Woude
- Center for Human Movement Sciences Groningen, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Center for Rehabilitation, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Victoria E Claydon
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC, Canada; International Collaboration On Repair Discoveries, Vancouver, BC, Canada.
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Lewis NCS, Ainslie PN, Atkinson G, Jones H, Grant EJM, Lucas SJE. Initial orthostatic hypotension and cerebral blood flow regulation: effect of α1-adrenoreceptor activity. Am J Physiol Regul Integr Comp Physiol 2013; 304:R147-54. [DOI: 10.1152/ajpregu.00427.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the hypothesis that α1-adrenergic blockade would lead to an inability to correct initial orthostatic hypotension (IOH) and cerebral hypoperfusion, leading to symptoms of presyncope. Twelve normotensive humans (aged 25 ± 1 yr; means ± SE) attempted to complete a 3-min upright stand, 90 min after the administration of either α1-blockade (prazosin, 1 mg/20 kg body wt) or placebo. Continuous beat-to-beat measurements of middle cerebral artery velocity (MCAv; Doppler), blood pressure (finometer), heart rate, and end-tidal Pco2were obtained. Compared with placebo, the α1-blockade reduced resting mean arterial blood pressure (MAP) (−15%; P < 0.01); MCAv remained unaltered ( P ≥ 0.28). Upon standing, although the absolute level of MAP was lower following α1-blockade (39 ± 10 mmHg vs. 51 ± 14 mmHg), the relative difference in IOH was negligible in both trials (mean difference in MAP: 2 ± 2 mmHg; P = 0.50). Compared with the placebo trial, the declines in MCAv and PetCO2during IOH were greater in the α1-blockade trial by 12 ± 4 cm/s and 4.4 ± 1.3 mmHg, respectively ( P ≤ 0.01). Standing tolerance was markedly reduced in the α1-blockade trial (75 ± 17 s vs. 180 ± 0 s; P < 0.001). In summary, while IOH was little affected by α1-blockade, the associated decline in MCAv was greater in the blockade condition. Unlike in the placebo trial, the extent of IOH and cerebral hypoperfusion failed to recover toward baseline in the α1-blockade trial leading to presyncope. Although the development of IOH is not influenced by the α1-adrenergic receptor pathway, this pathway is critical in the recovery from IOH to prevent cerebral hypoperfusion and ultimately syncope.
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Affiliation(s)
- Nia C. S. Lewis
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada
| | - Greg Atkinson
- Health and Social Care Institute, Teesside University, Middlesbrough, United Kingdom
| | - Helen Jones
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Emily J. M. Grant
- Department of Physiology, University of Otago, Dunedin, New Zealand; and
| | - Samuel J. E. Lucas
- Department of Physiology, University of Otago, Dunedin, New Zealand; and
- School of Physical Education, University of Otago, Dunedin, New Zealand
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Kiviniemi AM, Frances MF, Rachinsky M, Craen R, Petrella RJ, Huikuri HV, Tulppo MP, Shoemaker JK. Non-alpha-adrenergic effects on systemic vascular conductance during lower-body negative pressure, static exercise and muscle metaboreflex activation. Acta Physiol (Oxf) 2012; 206:51-61. [PMID: 22591110 DOI: 10.1111/j.1748-1716.2012.02447.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 02/27/2012] [Accepted: 04/16/2012] [Indexed: 11/28/2022]
Abstract
AIM This study tested the hypothesis that non-α-adrenergic mechanisms contribute to systemic vascular conductance (SVC) in a reflex-specific manner during the sympathoexcitatory manoeuvres. METHODS Twelve healthy subjects underwent lower-body negative pressure (LBNP, -40 mmHg) as well as static handgrip exercise (HG, 20% of maximal force) followed by post-exercise forearm circulatory occlusion (PECO, 5 min each) with and without α-adrenergic blockade induced by phentolamine (PHE). Aortic blood flow, finger blood pressure and superficial femoral artery blood flow were measured to calculate cardiac output, SVC and leg vascular conductance (LVC) during the last minute of each intervention. RESULTS Mean arterial pressure (MAP) decreased more during LBNP with PHE compared with saline (-7 ± 7 vs. -2 ± 5%, P = 0.016). PHE did not alter the MAP response to HG (+20 ± 12 and +24 ± 16%, respectively, for PHE and saline) but decreased the change in MAP during PECO (+12 ± 7 vs. +21 ± 14%, P = 0.005). The decrease in SVC and LVC with LBNP did not differ between saline and PHE trials (-13 ± 10 vs. -17 ± 10%, respectively, for SVC, P = 0.379). In contrast, the SVC response to HG increased from -9 ± 12 with saline to + 5 ± 15% with PHE (P = 0.002) and from -16 ± 15 with saline to +1 ± 16% with PHE during PECO (P = 0.003). LVC responses to HG or PECO were not different from saline with PHE. CONCLUSIONS Non-α-adrenergic vasoconstriction was present during LBNP. The systemic vasoconstriction during static exercise and isolated muscle metaboreflex activation, in the absence of leg vasoconstriction, was explained by an α-adrenergic mechanism. Therefore, non-α-adrenergic vasoconstriction is more emphasized during baroreflex, but not metaboreflex-mediated sympathetic activation.
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Affiliation(s)
| | - M. F. Frances
- School of Kinesiology; The University of Western Ontario; London; ON; Canada
| | - M. Rachinsky
- Department of Anesthesia and Perioperative Medicine; The University of Western Ontario; London; ON; Canada
| | - R. Craen
- Department of Anesthesia and Perioperative Medicine; The University of Western Ontario; London; ON; Canada
| | - R. J. Petrella
- School of Kinesiology; The University of Western Ontario; London; ON; Canada
| | - H. V. Huikuri
- Institute of Clinical Medicine; The University of Oulu; Oulu; Finland
| | | | - J. K. Shoemaker
- School of Kinesiology; The University of Western Ontario; London; ON; Canada
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Lewis NCS, Ainslie PN, Atkinson G, Jones H, Grant EJM, Lucas SJE. The Effect of Time-of-Day and Sympathetic α1-Blockade on Orthostatic Tolerance. Chronobiol Int 2012; 29:882-90. [DOI: 10.3109/07420528.2012.699121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Snyder KAM, Shamimi-Noori S, Wilson TE, Monahan KD. Age- and limb-related differences in the vasoconstrictor response to limb dependency are not mediated by a sympathetic mechanism in humans. Acta Physiol (Oxf) 2012; 205:372-80. [PMID: 22276905 DOI: 10.1111/j.1748-1716.2012.02416.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 11/30/2011] [Accepted: 01/16/2012] [Indexed: 11/30/2022]
Abstract
AIMS We tested the hypotheses that vasoconstrictor responses to limb dependency are: (i) greater in the leg than the arm, (ii) impaired with age and (iii) not sympathetically mediated. METHODS Vascular responses to limb dependency (i.e. lowering the limb from heart level to 30 cm below heart level) were determined in 17 young and 17 older adults. Indices of blood flow were obtained in the brachial and popliteal arteries (Doppler ultrasound) as well as in the cutaneous circulation (forearm and calf using laser-Doppler flowmetry). Vasoconstriction was quantified by calculating the indices of vascular resistance as height corrected mean arterial pressure/limb blood velocity or skin flux. A second group of subjects repeated the limb dependency trials after acute systemic sympathetic blockade. RESULTS Limb dependency increased vascular resistance index in the brachial artery (∆59 ± 8%; P<0.05) and popliteal artery (∆99 ± 10%; P<0.05 for change in heart level and brachial vs. popliteal) of young and older adults (∆60 + 9% brachial and ∆61 ± 7% popliteal arteries; P<0.05 for change in heart level and response in popliteal young vs. older adults). In contrast, cutaneous vasoconstrictor responses to limb dependency were similar in the forearm (∆218 ± 29% and ∆200 ± 29% for young and older adults, respectively) and calf (∆257 ± 32% and ∆236 ± 29%; all P<0.05 from heart level) of young and older adults. Vasoconstrictor responses to limb dependency were not affected by sympathetic blockade in young or older adults. CONCLUSION These findings indicate that age-, limb-, and tissue-related differences may exist in the vasoconstrictor response to limb dependency in healthy humans, which are not sympathetically mediated.
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Affiliation(s)
- K. A. M. Snyder
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
| | - S. Shamimi-Noori
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
| | - T. E. Wilson
- Departments of Biomedical Sciences & of Specialty Medicine; Ohio University Heritage College of Osteopathic Medicine; Athens; OH; USA
| | - K. D. Monahan
- Penn State Heart and Vascular Institute; Pennsylvania State University College of Medicine; Hershey; PA; USA
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Groothuis JT, Thijssen DHJ, Lenders JWM, Deinum J, Hopman MTE. Leg vasoconstriction during head-up tilt in patients with autonomic failure is not abolished. J Appl Physiol (1985) 2011; 110:416-22. [PMID: 21127209 DOI: 10.1152/japplphysiol.01098.2010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maintaining blood pressure during orthostatic challenges is primarily achieved by baroreceptor-mediated activation of the sympathetic nervous system, which can be divided into preganglionic and postganglionic parts. Despite their preganglionic autonomic failure, spinal cord-injured individuals demonstrate a preserved peripheral vasoconstriction during orthostatic challenges. Whether this also applies to patients with postganglionic autonomic failure is unknown. Therefore, we assessed leg vasoconstriction during 60° head-up tilt in five patients with pure autonomic failure (PAF) and two patients with autonomic failure due to dopamine-β-hydroxylase (DBH) deficiency. Ten healthy subjects served as controls. Leg blood flow was measured using duplex ultrasound in the right superficial femoral artery. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. DBH-deficient patients were tested off and on the norepinephrine pro-drug l-threo-dihydroxyphenylserine (l-DOPS). During 60° head-up tilt, leg vascular resistance increased significantly in PAF patients [0.40 ± 0.38 (+30%) mmHg·ml−1·min−1]. The increase in leg vascular resistance was not significantly different from controls [0.88 ± 1.04 (+72%) mmHg·ml−1·min−1]. In DBH-deficient patients, leg vascular resistance increased by 0.49 ± 0.01 (+153%) and 1.52 ± 1.47 (+234%) mmHg·ml−1·min−1 off and on l-DOPS, respectively. Despite the increase in leg vascular resistance, orthostatic hypotension was present in PAF and DBH-deficient patients. Our results demonstrate that leg vasoconstriction during orthostatic challenges in patients with PAF or DBH deficiency is not abolished. This indicates that the sympathetic nervous system is not the sole or pivotal mechanism inducing leg vasoconstriction during orthostatic challenges. Additional vasoconstrictor mechanisms may compensate for the loss in sympathetic nervous system control.
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Affiliation(s)
- Jan T. Groothuis
- Departments of 1Physiology and
- Department of Rehabilitation, Sint Maartenskliniek, Nijmegen, The Netherlands
| | - Dick H. J. Thijssen
- Departments of 1Physiology and
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; and
| | - Jacques W. M. Lenders
- Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen
- Department of Medicine III, Carl Gustav Carus University Medical Center, Dresden, Germany
| | - Jaap Deinum
- Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen
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Groothuis JT, Rongen GA, Geurts AC, Smits P, Hopman MT. Effect of different sympathetic stimuli-autonomic dysreflexia and head-up tilt-on leg vascular resistance in spinal cord injury. Arch Phys Med Rehabil 2011; 91:1930-5. [PMID: 21112436 DOI: 10.1016/j.apmr.2010.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/19/2010] [Accepted: 09/01/2010] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To compare the effect of different sympathetic stimuli, that is, exaggerated sympathetic activity and orthostatic challenges, on the increase in leg vascular resistance in persons with spinal cord injury (SCI) without and controls with supraspinal sympathetic control. DESIGN Case-control intervention study. SETTING Physiology research laboratory. PARTICIPANTS Persons with SCI (N=9; motor and sensory complete spinal cord lesion above the sixth thoracic spinal segment) and able-bodied controls (N=9). INTERVENTIONS In persons with SCI, exaggerated sympathetic activity was evoked by autonomic dysreflexia, and in controls, by using a cold pressor test (CPT). A 30° head-up tilt (HUT) was performed in both groups. MAIN OUTCOME MEASURE Leg blood flow was measured by using venous occlusion plethysmography during the different sympathetic stimuli. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. RESULTS In persons with SCI, leg vascular resistance significantly increased during autonomic dysreflexia and 30° HUT (25±20 and 24±13 arbitrary units [AU], respectively), with no difference (P=.87) between stimuli. In controls, leg vascular resistance significantly increased during CPT and 30° HUT (15±13 and 29±12AU, respectively) with no difference (P=.03) between stimuli. There were no differences (P=.22) in increase in leg vascular resistance during the different sympathetic stimuli between persons with SCI and controls. CONCLUSIONS The increase in leg vascular resistance during autonomic dysreflexia in persons with SCI is not different from that during 30° HUT, which might be caused by a limited vasoconstrictor reserve. Despite the lack of supraspinal sympathetic control in persons with SCI, the increase in leg vascular resistance during exaggerated sympathetic activity was not different from controls.
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Affiliation(s)
- Jan T Groothuis
- Department of Physiology, Radboud University Nijmegen Medical Centre, The Netherlands
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Angiotensin II contributes to the increased baseline leg vascular resistance in spinal cord-injured individuals. J Hypertens 2010; 28:2094-101. [DOI: 10.1097/hjh.0b013e32833cd2f4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Groothuis JT, Rongen GA, Deinum J, Pickkers P, Danser AHJ, Geurts AC, Smits P, Hopman MT. Sympathetic Nonadrenergic Transmission Contributes to Autonomic Dysreflexia in Spinal Cord–Injured Individuals. Hypertension 2010; 55:636-43. [DOI: 10.1161/hypertensionaha.109.147330] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Autonomic dysreflexia is a hypertensive episode in spinal cord–injured individuals induced by exaggerated sympathetic activity and thought to be α-adrenergic mediated. α-Adrenoceptor antagonists have been a rational first choice; nevertheless, calcium channel blockers are primarily used in autonomic dysreflexia management. However, α-adrenoceptor blockade may leave a residual vasoconstrictor response to sympathetic nonadrenergic transmission unaffected. The aim was to assess the α-adrenergic contribution and, in addition, the role of supraspinal control to leg vasoconstriction during exaggerated sympathetic activity provoked by autonomic dysreflexia in spinal cord–injured individuals and by a cold pressure test in control individuals. Upper leg blood flow was measured using venous occlusion plethysmography during supine rest and during exaggerated sympathetic activity in 6 spinal cord–injured individuals and 7 able-bodied control individuals, without and with phentolamine (α-adrenoceptor antagonist) and nicardipine (calcium channel blocker) infusion into the right femoral artery. Leg vascular resistance was calculated. In spinal cord–injured individuals, phentolamine significantly reduced the leg vascular resistance increase during autonomic dysreflexia (8±5 versus 24±13 arbitrary units;
P
=0.04) in contrast to nicardipine (15±10 versus 24±13 arbitrary units;
P
=0.12). In controls, phentolamine completely abolished the leg vascular resistance increase during a cold pressure test (1±2 versus 18±14 arbitrary units;
P
=0.02). The norepinephrine increase during phentolamine infusion was larger (
P
=0.04) in control than in spinal cord–injured individuals. These results indicate that the leg vascular resistance increase during autonomic dysreflexia in spinal cord–injured individuals is not entirely α-adrenergic mediated and is partly explained by nonadrenergic transmission, which may, in healthy subjects, be suppressed by supraspinal control.
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Affiliation(s)
- Jan T. Groothuis
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Gerard A. Rongen
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Jaap Deinum
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Peter Pickkers
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - A. H. Jan Danser
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Alexander C.H. Geurts
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Paul Smits
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
| | - Maria T.E. Hopman
- From the Departments of Physiology (J.T.G., M.T.E.H.), Pharmacology-Toxicology (G.A.R., P.S.), General Internal Medicine (J.D.), Intensive Care Medicine (P.P.), and Rehabilitation (A.C.H.G.), Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Department of Rehabilitation (J.T.G., A.C.H.G.), Sint Maartenskliniek, Nijmegen, The Netherlands; Division of Pharmacology, Vascular and Metabolic Diseases (A.H.J.D.), Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands
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Walløe L. At least three levels of physiological control mechanisms ensure that arterial blood pressure is maintained in erect humans. Acta Physiol (Oxf) 2009; 195:303. [PMID: 19183356 DOI: 10.1111/j.1748-1716.2009.01958_1.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lars Walløe
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
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